The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Hub-and-spoke topologies may be used in telecommunications networks and typically involve one or more hub devices in relatively centralized logical positions coupled to other internetworking devices in spoke positions; traffic directed from one spoke device to another spoke device generally is routed through one or more of the hub devices. Consequently, the failure of one of the hub devices may be a significant issue and internetworking architects desire to improve the availability of such networks in the face of a failure of a hub. Implementations of high availability (HA) mechanisms in a allow redirecting data traffic away from a failed node in a relative short period of time. However, since the HA mechanisms are typically implemented using stateful switchover approaches, the implementations rarely ensure at least 99.999% availability of the network, which is a goal of some network managers to provide the best user experience.
Stateless, probe-based HA mechanisms are usually implemented in network configurations in which the spoke devices are multi-homed, and rely on routing protocols to determine whether data traffic is to be switched to other nodes. Examples of such protocols include the Dead Peer Detection (DPD) protocol or the routing protocol hold-time mechanism. However, such implementations are inherently slow and typically generate a significant amount of background traffic. An increase in the background traffic may be caused by a large amount of probes disseminated in a network, which may also cause obtaining false-positive results, and eventually destabilize the network.
In some HA implementations, the Bidirectional Forwarding Detection (BFD) protocol or the Internet-Key Exchange (IKE) protocol may be used. However, such implementations may cause issues with a network scalability and reliability similar to other stateless, probe-based mechanisms.